Pretreatment of olive mill wastewater by chitosan coagulation and advanced oxidation processes (original) (raw)
Related papers
Journal of hazardous …, 2009
Olive mills wastewater (OMW) is characterized by its high organic content and refractory compounds. In this study, an advanced technology for the treatment of the recalcitrant contaminants of OMW has been investigated. The technique used was either photo-Fenton as homogeneous photocatalytic oxidation or UV/semi-conductor catalyst (such as TiO 2 , ZrO 2 and FAZA) as heterogeneous photocatalytic oxidation for treatment of OMW. For both the processes, the effect of irradiation time, amounts of photocatalysts and semiconductors , and initial concentration of hydrogen peroxide has been studied. At the optimum conditions, photo-Fenton process achieved COD, TOC, lignin (total phenolic compounds) and total suspended solids (TSSs) removal values of 87%, 84%, 97.44% and 98.31%, respectively. The corresponding values for UV/TiO 2 were 68.8%, 67.3%, 40.19% and 48.9%, respectively, after 80 min irradiation time. The biodegradability expressed by BOD 5 /COD ratio for treated wastewater was ranged from 0.66 to 0.8 compared to 0.19 for raw wastewater indicating enhancement of biodegradation.
Biological and photo-Fenton treatment of olive mill wastewater
2008
Olive oil wastewaters (OOMW) are dark effluents which pose serious environmental problems. The aim of this work was to apply biological treatment with Pleurotus spp., and chemical treatment, through oxidation by Photo-Fenton, to OOMW. The biological treatment was not very efficient in colour reduction. In 25% OOMW dilution treated with P. sajor caju or P. ostreatus, high percentages of colour reduction (460 nm) were recorded after 6 days (70.3 and 54.7%) but, thereafter, great oscillations were observed. In terms of pH, a similar profile was recorded in 25-50% dilutions treated either with P. sajor caju or P. ostreatus. Both species grew in OOMW and were responsible for COD reduction, which was greater in the OOMW treated with P. sajor caju. The Photo-Fenton reaction was very efficient (> 90%) in colour reduction. The best combination of H 2 O 2 /Fe concentrations was found to be 6 ml of H 2 O 2 (70%) plus 1 ml of FeSO 4 (0,5M). In terms of toxicity reduction tested for Daphnia longispina, the biological and chemical treatments also had a different efficiency. Further research will be carried out to assess the combined application of both treatments, and it's effectiveness in the improvement of the main concerning properties of this industrial effluent.
Heterogeneous Photo-Fenton Reaction for Olive Mill Wastewater Treatment—Case of Reusable Catalyst
Catalysts
Heterogeneous catalysts can be an efficient and economical option for olive mill wastewater (OMW) treatment by an advanced oxidation process if they could be reused. In this work, OMW was treated using a heterogeneous photo-Fenton reaction (artificial ultraviolet light/H2O2/HFeO2). For this purpose, different concentrations of HFeO2 were tested: 0.04; 0.3; 0.8; 5.0; 10.0; 20.0; 30.0, and 50.0 g/L. The following operational conditions were chosen: pH = 3.0, temperature = 20 °C, agitation rate = 700 rpm. The experimental results showed high removal percentages of the main OMW characterization parameters at 50 g/L of HFeO2: %CODremoval = 62.8%; %total phenolic compounds (TPCs) = 88.9%. These results were also compared with those of other control oxidation systems, i.e., UV, H2O2, and UV/H2O2, which provided 35.5 and 56.1%; 46.2 and 74.0%; 48.0 and 76.8% removal, respectively. In addition, the catalyst was reused three times, recovering more than 90.5% of it.
Solar Energy, 2004
Olive mill wastewater (OMW), a highly polluted wastewater from the olive oil industry, was treated by solar photocatalysis and solar photo-Fenton. Among the tested systems the application of titanium dioxide alone was not successful. The addition of peroxydisulphate as an electron acceptor had only limited effect on degradation performance and led to high salt concentrations (30 g/l sulphate generated) and a pH value near zero. The photo-Fenton method successfully removed up to 85% COD and up to 100% of phenol index of OMW with different initial concentrations and from different sources. Two solar photocatalytic pilot-plant reactors were used; one of conventional CPC type and an open non-concentrating Falling Film Reactor. The latter, newly designed reactor worked properly and yielded comparable results to the CPC in terms of degradation rate referred to incident UV radiation energy per solution volume. The suspended solids in the OMW hinder light from entering the reactor. Therefore, flocculation induced by a commercial flocculation agent was successfully applied to remove suspended solids. Application of this pre-treatment led to considerable increase of degradation rates and decrease of hydrogen peroxide consumption.
Photochemical UV/TiO2 treatment of olive mill wastewater (OMW)
Bioresource Technology, 2008
Olive mill wastewater (OMW) was treated by photocatalysis using TiO 2 under UV irradiation on the laboratory scale. The chemical oxygen demand, the coloration at 330 nm, and the level of phenols all showed decreases which, after a 24-h treatment, reached 22%, 57% and 94%, respectively. The differences between these three values indicate the persistence of colourless, non-phenolic compounds. Application of the novel Fictitious Atomic-Group Separation method showed an increase in carbon oxidation state and confirmed that the attack primarily concerns, aromatic moieties. A fine spectroscopic study revealed the occurrence of three successive phases during the degradation process, thought to correspond to three different categories of molecules in the OMW and the presence of pectin compounds.
Chemical Engineering Journal, 2009
Pre-treatment of olive mill wastewater (OMW) by Fenton Oxidation with zero-valent iron and hydrogen peroxide was investigated to improve phenolic compounds degradation and the chemical oxygen demand (COD) removal. Experimental procedure is performed with diluted OMW with COD 19 g/L and pH 5.2. The application of zero-valent Fe/H 2 O 2 procedure allows high removal efficiency of pollutants from OMW. The optimal experimental conditions were found to be continuous presence of iron metal, acidic pH (2-4) and 1 M hydrogen peroxide solution. The experimental results show that the removal of 1 g of COD need 0.06 M of H 2 O 2 . At pH 1, the maximum COD removal (78%) is achieved after 1 h. Therefore, with a pH value within 2 and 4 the maximum COD removal reached 92%. Phenolic compounds are identified in treated and untreated OMW by gas chromatography coupled to mass spectrometry (GC-MS). The result shows a total degradation of phenolic compounds and an increasing biodegradability of treated OMW.
Catalysts
The high production of raw olive oil mill wastewater (OMW) is a current environmental problem due to its high organic load and phenol compounds. In this work, photo-Fenton reaction as an advanced oxidation process has been chosen for OMW treatment. In this sense, different iron salts (FeCl3, Fe2(SO4)3, FeSO4·7H2O, and Fe(ClO4)3) as catalysts were used in order to compare their effects on treatment. For each catalyst, different H2O2 concentrations (2.5, 5.0, 7.5, 10.0, 15.0, 20.0, and 30.0%, w/v) as oxidizing agents were tested. The common experimental conditions were temperature 20 °C, the catalyst/H2O2 ratio = 0.03, pH = 3, and ultraviolet light. The Lagergren kinetic model, in cases of total organic carbon removal, for the best H2O2 concentration per catalyst was used. During the experiments, the water quality was determined by measuring the removal percentages on chemical oxygen demand, total carbon, total organic carbon, total nitrogen, total phenolic compounds, total iron, turb...
Photocatalytic treatment of black table olive processing wastewater
The photocatalytic treatment of an effluent from black table olive processing over TiO 2 suspensions was investigated. The study focused on the effect of various operating parameters on the treatment efficiency including initial organic load, catalyst type, concentration and reuse, and addition of hydrogen peroxide. Initial organic load, expressed in terms of chemical oxygen demand (COD), was studied in the range 1-8 g/L, anatase TiO 2 concentrations in the range 0.25-2 g/L and H 2 O 2 concentrations in the range 0.025-0.15 g/L. Treatment efficiency, which was assessed in terms of COD, total phenols, aromatics and color reduction, generally increased with decreasing initial COD and increasing contact time, catalyst and H 2 O 2 concentrations; however, for H 2 O 2 there was a maximum dosage above which performance deteriorated. Depending on the conditions employed, nearly complete decoloration (>90%) could be achieved, while mineralization never exceeded 50%. Shake-flask tests with non-acclimated activated sludge showed that both the original and photocatalyzed effluents were degradable aerobically with the biodegradation rate of the original effluent being three times greater than the oxidized one. On the other hand, photocatalytic oxidation of the original effluent was at least two orders of magnitude faster than its biological oxidation to achieve comparable levels of degradation.